Endless transfer conveyers for transferring frozen foodstuff in refrigeration rooms are disclosed in Japanese Patent Publication No. 7-100524 (prior art 1), No. 7-25407 (prior art 2), and No. 1-44605 (prior art 3). Each of the conveyers comprises a plurality of transfer pieces connected to be capable of moving relative to each other along the transfer direction to constitute a transfer passage of frozen foodstuff, etc., the transfer piece being composed of connection members and flat spacer members erecting on both sides of the connection members, and the plurality of transfer pieces are piled spirally vertically such that the lower end of a transfer piece in the spiral pile rides on the upper end of a transfer piece positioned right under said transfer piece vertically adjacent thereto.
FIG.18 is an outside view of the spirally piled endless transfer conveyer disclosed in said prior arts. In the drawing, reference numeral 100 is a spirally piled transfer conveyer comprising transfer pieces 010, each transfer piece being composed of connection members 02 with flat spacer members provided to erect on both sides of the connection members 02.
Particularly in prior art 1 among said prior arts, the transfer conveyer comprises a plurality of transfer pieces for forming a transfer passage, each of the transfer piece is composed of connection members with flat spacer members attached to stand upright on both sides of the connection members and connected to each other to be capable of moving along the transfer direction, and each of the flat spacer members is formed to have an inside-part and an outside-part continuing to the inside-part and offsetting from the inside-part outward in a lateral direction perpendicular to the transfer direction. The lower end part of the outside-part of the spacer member is bent outward to form an outwardly inclined part, and the lower end part of the inside-part of the spacer is bent inward to form an inwardly inclined part. Therefore, the upper end of a spacer member in the spiral is guided by the outwardly inclined part and inwardly inclined part of a spacer member positioned right under said spacer member and lateral movement of the spacer member in lateral directions perpendicular to the transfer direction is restrained. Thus, the plurality of transfer pieces can be piled vertically spirally with the occurrence of lateral movement of the transfer pieces in lateral directions perpendicular to the transfer direction prevented.
However, in prior art 1, as the upper end of the outside-part of the spacer member contacts the outwardly inclined face in line contact, there occurs high contact pressure which causes a problem that wear will be generated due to the high contact pressure.
Further, in prior art 1, the upper end of the outside-part of a spacer member is guided by the outwardly inclined part of the outer-side of the spacer member positioning right above, the upper end of the inside-part of a spacer member is guided by the inwardly inclined part of the spacer member positioning right above, and the position of the outwardly inclined part is different from that of the inwardly inclined part in the direction along the transfer direction, so that variation in engagement is apt to occur for each spacer member, which induces zig.zag motion of each of the transfer pieces, that is, each of the transfer pieces travel wobbling right and left. As a result, it is difficult to secure stable operation of the transfer conveyer when the transfer pieces are piled in a spiral.
Still further, in prior art 1, as the spacer member is formed to have an outwardly inclined part at the lower end part of the outside-part thereof and an inwardly inclined part at the lower end of the inside-part thereof, processing man-hour of the spacer member increases and also assembling man-hour increases to engage the upper end of the spacer member with the inclined parts formed in the lower end part of the spacer member right above in the spiral, resulting in an increase manufacturing and assembling cost of the transfer conveyer.
In prior art 1 and 2, as the surface of the connection members of the transfer pieces to form the transfer passage contact the surface of driving members such as a drive roller, drive chain, etc., there may occur a sanitary problem when foodstuff is transferred.
Further, in prior art 1 and 2, the inside chain for driving the inner side of the transfer conveyer and the outside chain for driving the outer side of the transfer conveyer are driven by separate motors, and rotation speed of each motor is controlled separately. Therefore, two motors and associated parts are needed to drive the transfer conveyer. As a result, the driving apparatus for driving the chains becomes complicated resulting in an increased price.
Still further, in prior art 1 and 2, each motor for driving the transfer conveyer is installed vertically, the height of the driving apparatus is increased and its maintainability is not good for the speed change gear drive and motor is installed vertically.
As mentioned above, there are several problems to be solved in the prior arts.